Electrochemical analytical sensors are commonly used to determine the presence and concentration of a biological analyte. Such sensors are used, for example, to monitor blood glucose levels in diabetic patients.
Although many currently available sensor strip products require relatively large sample volumes, e.g., generally requiring 3 μL or more of blood or other biological fluid, there has been a trend for small volume sizes, such as 1 μL and less. For example, U.S. Pat. Nos. 6,143,164, 6,338,790 and 6,616,819 provide various configurations of small volume (i.e., less than 1 μL) sensors.
As the volume of sample chambers in the sensors decreases, it becomes increasingly more difficult to fill the sample chamber with the sample to be analyzed.
An attempt has been made, in U.S. Pat. No. 6,071,391, to provide an electrochemical sensor strip that easily receives the sample to be analyzed. The sample chamber is designed to be partially open at the peripheral part and partially closed by an internal adhesive layer.
As electrochemical sensors continue to be used, there continues to be an interest in electrochemical sensors that utilize a small sample volume of biological fluid for analysis and which are easy to fill with sample.